The present invention relates to collet chucks and in particular to improved structure for increasing the clamping pressure of such chucks.
In the prior art, many collet chucks have been mechanically operated between clamping and releasing positions by a toggle and drawbar system. More recently, pneumatically operated collet chucks have been provided in which a pneumatic cylinder urges the collet between clamping and releasing positions. With such prior art systems, the size of the chuck as well as the chucking pressure on a workpiece is significantly limited in the case of feed through type chucks. This in turn limits the size of a workpiece which can be accommodated as well as the speed of rotation.
There exists therefore a need for an improved collet chuck which can handle relatively large diameter workpieces which must be rotated at relatively high speeds.